JPH0533309Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a mold used for two-color molding, and more particularly to a mold with an improved undercut processing mechanism.

[Prior Art] In a mold for forming a molded body having an undercut portion, a method using an inclined pin extending from a fixed mold as a processing mechanism for the undercut portion is known. That is, as disclosed in Japanese Utility Model Publication No. 63-34900, for example, there is a method in which an inclined pin is engaged with a slide core and the slide core is slid by the force of opening the mold to release the undercut portion from the mold. be.

[Problem to be solved by the invention] However, when this method is applied to two-color formation, a difficult problem arises. That is, as shown in FIG. 4, first the undercut portion 201 is
A primary molded body 200 having a shape is formed by a first fixed mold 100 and a movable mold 110. Next, the first fixed mold 100
is replaced with the second fixed mold for the secondary formed body, but at this time, since the inclined pin 101 extending from the first fixed mold 100 is engaged with the slide core 102, as shown in FIG. The slide core 102 slides and moves at the same time as the mold is opened, and the undercut portion 201 is released from the mold. When the second fixed mold 103 for the secondary molded body is clamped with the movable mold 110, the inclined pin 104 engages with the slide core 102, and the slide core 102 is again undercut as shown in FIG. 201. Then, molten resin is injected between the primary molded body 200 and the second fixed mold 103 to form a secondary molded body 210. However, with this method, when the slide core 102 that has once come out reenters the undercut portion 201, there is a risk that the undercut portion 201 may be scratched or damaged.

In order to avoid such problems, (1) 7th
As shown in the figure, there is a method of increasing the draft taper angle of the undercut part 201, (2) a method of performing secondary molding without inserting the slide core into the undercut part, and (3) a method of molding as shown in Figure 8. A method using an inclined core 300 that uses extrusion force without using opening force, (4) As shown in FIG. 9, a hydraulic cylinder 40
Possible methods include a method of independently sliding the slide cores at 0 or the like.

However, method (1) may be difficult to implement due to product design constraints. In method (2), the undercut portion becomes hollow during secondary molding, so there is a risk that the primary molded product may be damaged by injection pressure. In method (3), the molded body may adhere to the inclined core 300, making it difficult to release from the mold, and the mold structure also becomes complicated. Furthermore, even if multi-stage extrusion is performed, the inclined core 30
0 may enter the undercut portion again, and in this case, the mold may be damaged. In method (4),
In two-color molding, the movable mold generally rotates, making it difficult to design hydraulic piping and other components, which increases the cost of the mold.

The present invention was devised in view of the above circumstances, and aims to process an undercut portion in a two-color mold with a structure as simple as possible and without the above-mentioned problems.

[Means for Solving the Problem] The two-color molding mold of the present invention includes a movable mold, a first fixed mold that forms a primary molded body together with the movable mold, and a secondary mold that is adjacent to the primary molded body together with the movable mold. A second fixed mold that forms a molded body, a slide core that slides into sliding contact with the movable mold so as to be movable in a direction intersecting the mold opening direction and forms an undercut portion of the primary molded body, and a direction toward and away from the movable mold. a second extrusion plate interposed between the first extrusion plate and the movable mold and driven in a direction toward and away from the movable mold by the pressing force from the first extrusion plate; , engages with a slide core consisting of a shaft part whose one end is fixed to the first extrusion plate and extends in the driving direction of the first extrusion plate, and a head part which extends from the other end of the shaft part at an angle with respect to the axial direction of the shaft part. A cam that slides with one end fixed to the second extrusion plate and a second cam with one end fixed to the second extrusion plate.
It consists of an extrusion pin whose other end protrudes from the mold surface of the movable mold by driving the extrusion plate, and after the primary molded body and the secondary molded body are formed and the second fixed mold and the movable mold are opened, the first extrusion is performed. The present invention is characterized in that the plate is driven and then the second extrusion plate is driven.

[Operations and Effects of the Invention] In the two-color mold of the present invention, the slide core is operated not by the force of opening and closing the mold, but by the driving force of the extrusion plate. Furthermore, since two push-out plates are provided and a cam is used, there is a time difference between driving the slide core and driving the push-out pin.

That is, until the primary molded body and the secondary molded body having the undercut portion are formed, the extrusion plate is not driven, and therefore the slide core is molded in a fixed state. Therefore, the undercut portion will not be damaged or damaged. Furthermore, damage to the primary molded body due to injection pressure does not occur. When releasing the two-color molded product, the second fixed mold and the movable mold are first opened. Next, the first extrusion plate is driven to cause the slide core to slide and come out of the undercut portion, and then the second extrusion plate is driven to cause the extrusion pin to rise and the molded article to be released from the movable mold. Therefore, there is no problem such as the molded body adhering to the slide core and making release from the mold difficult.

Therefore, according to the mold of the present invention, the undercut portion can be reliably processed without various problems, the structure is simple, and the mold cost increases only slightly, resulting in an inexpensive mold.

[Example] Hereinafter, this will be explained in detail using examples.

FIGS. 1 to 3 show a mold according to an embodiment of the present invention. This mold includes a movable mold 1, a first fixed mold (not shown) that forms a primary molded body 20, and a secondary molded body 2.
2, a slide core 10 in sliding contact with the movable mold 1, a first extrusion plate 3, a second extrusion plate 4 interposed between the first extrusion plate 3 and the movable mold 1, 1 a dogleg cam 5 having one end fixed to the second pushing plate 3; a pushing pin 6 having one end fixed to the second pushing plate 4; and a positioning collar fixed to the second pushing plate 4 and projecting toward the first pushing plate 3. 7 and a return pin 8 fixed to the first extrusion plate 3.

The slide core 10 slides on the movable mold 1 so as to be movable in a direction perpendicular to the mold opening and mold closing directions, and forms an undercut portion 21 of the primary molded body 20. This slide core 10 is provided with a guide groove 11 for guiding the dogleg cam 5.

Both the first extrusion plate 3 and the second extrusion plate 4 are configured to be movable in the direction toward and away from the movable mold 1. Note that the first extrusion plate 3 is pressed and moved by the ejector rod 30 of the molding machine, and the second extrusion plate 4 is moved by the ejector rod 30 of the molding machine.
It comes into contact with the first extrusion plate 3, which is being pressed, and is pressed and moved.

The dogleg cam 5 includes a shaft portion 50 whose one end is fixed to the first extrusion plate 3, and a head portion 51 extending at the other end side of the shaft portion 50 at an angle with respect to the axial direction of the shaft portion 50. The head 51 extends in the mold opening/closing direction of the movable mold 1 and passes through the second extrusion plate 4 and the movable mold 1, and the head 51 is connected to the guide groove 11 of the slide core 10.
is engaged with.

A spring 40 is provided between the movable die 1 and the second extrusion plate 4, and urges the second extrusion plate 4 in a direction closer to the first extrusion plate 3. The movement of the second extrusion plate 4 is regulated by the positioning collar 7 coming into contact with the mounting plate 12, and at this point the tip of the extrusion pin 6 is aligned with the mold surface of the movable mold 1. The positioning collar 7 has a large-diameter flange 70 at one end, and is locked to the first extrusion plate 3 by being inserted into a through hole 31 provided in the first extrusion plate 3 and engaging with the flange 70. . Also, the return pin 8 is connected to the second extrusion plate 4.
and is configured to be able to penetrate the movable mold 1 and protrude from the mold dividing surface.

A method of two-color molding using the mold of this embodiment configured as described above will be described.

First, as shown in FIG. 1, with the first push-out plate 3 in contact with the mounting plate 12, the dogleg cam 5
The head 51 of the slide core 10 engages with the slide core 10 so that the undercut portion 21 can be formed. Further, the positioning collar 7 is in contact with the mounting plate 12, and the tip surface of the extrusion pin 6 is aligned with the mold surface of the movable mold.
In this state, the movable mold 1 is clamped with a first fixed mold (not shown), and a primary molded body 20 is formed by injection molding.

Next, the first fixed mold and the movable mold 1 are opened, but at this time, the dogleg cam 5 and the like are fixed to the first extrusion plate 3, so they are not driven by the force of opening the mold, as shown in FIG. maintain the state of Therefore, the slide core 10 also does not move and the inside of the undercut portion 21 is filled, so that the undercut portion 21 is not damaged or damaged. As shown in FIG. 1, the second fixed mold 2 is connected to the movable mold 1
The mold is clamped, and a secondary molded body 22 is formed on the surface of the primary molded body 20 by injection molding. At this time as well, since the inside of the undercut part 21 is filled with the slide core 10, there is no problem of the undercut part 21 being deformed by the injection pressure.

After the molded body is cooled and solidified, when the second fixed mold 2 and the movable mold 1 are opened, the ejector rod 30 is driven and the first extrusion plate 3 is pressed. As a result, the first push-out plate 3 moves in a direction approaching the second push-out plate 4, as shown in FIG. Along with this movement, the dogleg cam 5 moves to protrude from the movable mold 1, and the engagement of the head 51 with the guide groove 11 causes the slide core 10 to slide in a direction perpendicular to the mold opening direction. At this time, the second push-out plate 4 remains stationary, so the push-out pin 6
The end face of is located on the mold surface of the movable mold 1. Therefore, the primary molded body 20 remains attached to the movable mold 1 and is prevented from being attached to the slide core 10 and removed, so that the slide core 10 is smoothly released from the undercut portion 21.

When the first extrusion plate 3 comes into contact with the second extrusion plate 4, the pressing force of the ejieku rod 30 is transmitted to the second extrusion plate 4, and the first extrusion plate 3
The second extrusion plate 4 is pressed in a direction closer to the movable die 1 against the urging force of. Then, as shown in FIG. 3, the ejecting pin 6 protrudes from the mold surface of the movable mold 1.
The primary molded body 20 and the secondary molded body 22 are moved into the movable mold 1.
Release from the mold. At this time, since the shaft portion 50 of the dogleg cam 5 is engaged with the guide groove 11, the slide core 10 is prevented from moving from that position.

When the molded body is taken out, the first fixed mold is replaced by the movable mold 1.
The mold is clamped. At this time, when the ejector rod 30 retreats, the second
The push-out plate 4 and the first push-out plate 3 move in a direction approaching the mounting plate 12. Then, the head 51 of the dogleg cam 5 engages with the slide core 10, and the slide core 10 moves to the position where the undercut portion 21 is formed. Then, the return pin 8 is pressed by the first fixed mold, and the first extrusion plate 3 is moved to the mounting plate 12.
Return to the predetermined position where it is in contact with. Note that even if the movement of the second push-out plate 4 is insufficient, the collar portion 70 of the positioning collar 7 engages with the first push-out plate 3, so that the second push-out plate 4
The push-out plate 4 reliably moves to the initial state. As a result, the end surface of the extrusion pin 6 becomes flush with the mold surface, thereby preventing damage to the mold. Then, the next molding process is performed.

That is, according to the mold of this embodiment, the undercut portion can be processed smoothly without any problems. Furthermore, compared to conventional molds, only one extrusion plate is required, and the mold structure is simple. Therefore, the increase in mold cost can be kept to a minimum, which is advantageous from a cost standpoint.

[Brief explanation of the drawing]

Figures 1 to 3 relate to a two-color molding mold according to an embodiment of the present invention, in which Figure 1 is a cross-sectional view of the main part when molding is completed, Figure 2 is a cross-sectional view of the main part at the initial stage of mold release, and Fig. Figure 3 is a sectional view of the main part at the final stage of mold release. 4 to 9 are reference diagrams showing an undercut processing mechanism different from the present invention, and FIGS. 4, 5, and 6 are explanatory diagrams showing a case where an inclined pin is used, and The figure is an explanatory diagram showing the case where the shape of the undercut part is changed.
FIG. 8 is an explanatory diagram showing the case where an inclined core is used, and FIG. 9 is an explanatory diagram showing the case where a hydraulic cylinder is used. 1...movable type, 2...second fixed type, 3...first
Extrusion plate, 4... Second extrusion plate, 5... Dogleg cam, 6... Extrusion pin, 7... Positioning collar, 8... Return pin, 10... Slide core, 11... Guide groove, 20... Primary Molded object, 2
2...Secondary molded body, 21...Undercut part,
40...Spring, 50...Shaft portion, 51...Head.

Claims (1)

[Claims for Utility Model Registration] A movable mold, a first fixed mold that forms a primary molded body together with the movable mold, and a second fixed mold that forms a secondary molded body that is adjacent to the primary molded body together with the movable mold. a slide core movably movable in a direction intersecting the mold opening direction and slidingly in contact with the movable mold to form an undercut portion of the primary molded body; an extrusion plate, a second extrusion plate interposed between the first extrusion plate and the movable mold and driven in a direction toward and away from the movable mold by a pressing force from the first extrusion plate; The slide core includes a shaft portion fixed to the first extrusion plate and extending in the driving direction of the first extrusion plate, and a head portion extending from the other end of the shaft portion at an angle with respect to the axial direction of the shaft portion. a cam that engages with and slides, and an extrusion pin that has one end fixed to the second extrusion plate and whose other end protrudes from the mold surface of the movable mold when the second extrusion plate is driven; After the body and the secondary molded body are formed and the second fixed mold and the movable mold are opened, the first extrusion plate is driven, and then the second extrusion plate is driven.
A two-color molding die characterized in that the extrusion plate is driven.